Quick IAC question
What should the IAC counts be at idle? I'm showing around 12, is that too high or low?
Thanks! |
That sounds pretty good to me. You want enough so that the ECM is in control. 5 or more is probably pretty acceptable. Is that with the car fully warmed up?
|
Originally Posted by ShawnZR-1
(Post 1563416812)
What should the IAC counts be at idle? I'm showing around 12, is that too high or low?
Thanks! Shawn, Twelve is fine. I've always tried for less, say 5-8. You can crack open the TB a bit to bring the IAC counts down. The bigger the TB, the more you want air to go thru the throttle blades and not bypass via the IAC opening. Keeps up the air velocity. :thumbs: |
Why would the air have any more or less velocity once in the plenum? Also, is velocity relevant at idle?
|
Maintaining good velocity through the throttle bores is really only a priority for TBI systems, where the fuel is added at the TB. It helps prevent puddling and helps atomization.
The benefit of low IAC counts for a port injected engine is more about how responsive the engine is to transients and coming back to idle. I also tune for high single digit IAC counts at idle, which takes most of the air control away from the IAC program. With the motor able to hold a good idle on its own without relying on the bypass air, then I can get more aggressive with things like the throttle follower action and decay rates. The result is an engine that has a quick response to throttle tip, and a very fast recovery to idle speed. Todd |
i have a? on both my 90s my Iac when cold is around 29 when they are fully warm they are 0. both cars run really good but am IO missing a problem
|
Possibly a vacuum leak preventing the engine from reaching the warm idle speed. The IAC is fully closed (zero steps), but the idle speed is still above the calibrated value. What is your observed warm idle rpm?
Also possible, but less likely, is that the throttle blades could be misadjusted, allowing too much air to enter when closed. Todd |
My 91 shows 20 stock chip 675rpms and 30 with SGC chip 900rpms
|
Wow, great information guys! Thanks!
Steve, I don't know if I've ever seen counts that high, of course, I've only scanned one other ZR-1! :lol: I'm by no means an expert here! :nono: One question: Why don't I see an IAC follower table in TunerPro RT? Does it exist for a '91? |
Originally Posted by ShawnZR-1
(Post 1563424577)
Wow, great information guys! Thanks!
Steve, I don't know if I've ever seen counts that high, of course, I've only scanned one other ZR-1! :lol: I'm by no means an expert here! :nono: One question: Why don't I see an IAC follower table in TunerPro RT? Does it exist for a '91? |
Originally Posted by tpepmeie
(Post 1563422118)
Possibly a vacuum leak preventing the engine from reaching the warm idle speed. The IAC is fully closed (zero steps), but the idle speed is still above the calibrated value. What is your observed warm idle rpm?
Also possible, but less likely, is that the throttle blades could be misadjusted, allowing too much air to enter when closed. Todd |
Originally Posted by ShawnZR-1
(Post 1563424577)
Wow, great information guys! Thanks!
Steve, I don't know if I've ever seen counts that high, of course, I've only scanned one other ZR-1! :lol: I'm by no means an expert here! :nono: One question: Why don't I see an IAC follower table in TunerPro RT? Does it exist for a '91? Todd, My TBI's were 2.13". I didn't need extra flow coming from the IACs. I minimized IAC steps to: 1. Maintain a smoother idle even while using a cam with a 108d LSA. The Xfire motor uses "diffusers" below the TB to maintain swirl keeping fuel in suspension. 2. At part and full throttle, throttle response was significantly improved in much the same way as a "dry manifold" design. I agree that a goal of tuning is to have the ECM "intervene" as little as possible. The better the "mechanical" tune of the motor, the better the overall tune is. The CW that "the ECM will take care of it" is bogus. |
...sooo, who wants to hack the code? :bigears: :)
|
Originally Posted by ShawnZR-1
(Post 1563434254)
...sooo, who wants to hack the code? :bigears: :)
|
waht are you using to read the IAC?
|
Originally Posted by phrogs
(Post 1563435291)
waht are you using to read the IAC?
|
Hmmm, so nobody wants to delve deeper into the code eh?
Well, I guess I can go without sleep for the next few weeks then... :) Time to dust off the binary side of the brain. |
Originally Posted by ShawnZR-1
(Post 1563458662)
Hmmm, so nobody wants to delve deeper into the code eh?
Well, I guess I can go without sleep for the next few weeks then... :) Time to dust off the binary side of the brain. Sounds like its all you..:thumbs: |
Originally Posted by We Gone
(Post 1563462713)
Sounds like its all you..:thumbs:
:lol: |
Originally Posted by ShawnZR-1
(Post 1563463683)
What are you talking about, all me? Get your butt up here and help me! :smash:
:lol: http://www.zr1netregistry.com/forum/index.php |
All times are GMT -4. The time now is 11:29 AM. |
© 2024 MH Sub I, LLC dba Internet Brands